Exploring, drilling and completing hydrocarbon and other wells are generally complicated, time consuming and ultimately very expensive endeavors. As a result, over the years, well architecture has become more sophisticated where appropriate in order to help enhance access to underground hydrocarbon reserves. For example, as opposed to land based oilfields accommodating wells of limited depth, it is not uncommon to find offshore oilfields with wells exceeding tens of thousands of feet in depth. Furthermore, today's hydrocarbon wells often include a host of lateral legs and fractures which stem from the main wellbore of the well toward a hydrocarbon reservoir in the formation.
Such subsea oilfields may accommodate a host of permanently installed equipment at the seabed. For example, in addition to wellhead Christmas tree assemblies and other architecture directly at each well, a host of pumps, manifolds, storage units and other equipment may be distributed about the oilfield according to the designated layout for the site.
As with any other oilfield equipment, whether on or off land, the periodic need for interventional maintenance may arise. Fortunately, in a large number of these circumstances, controlled fluid access alone may be sufficient to carry out the maintenance. That is, rather than pulling large scale equipment from the seabed to surface for hands on maintenance, it may be sufficient to hook up a hydraulic line to the equipment at the seabed and proceed with a service application. For example, a manifold at the seabed may be in need of a cleanout application. Thus, a diver or ROV (remote operated vehicle) may hook up a hydraulic line to the equipment and then a chemical injection application run to clean out the manifold.
Unfortunately, hooking up a hydraulic line to the equipment may be much easier said than done. For example, with ever increasing depths, the use of a diver for hands on installation is less practical, both in terms of the increased hazards and complexity. Further, even where an ROV is utilized, complexity and challenges remain when the effort to mate a small bore connector to a receptacle at a large piece of equipment.
An ROV may tightly secure a tubular small bore connector of perhaps about 2 inches or so in diameter and a few inches longer in length. The ROV may then be remotely guided toward the receptacle of the equipment as noted above. However, keep in mind that dragging from behind the connector is an extended, fluid filled, hydraulic line. The line may run several hundred feet toward a tank at the seabed or further, to a vessel at the surface where the chemical treatment fluid is stored. Regardless, a disorienting drag or torque is placed at one end of the connector which can have an impact on the ability of the ROV to properly align and engage the connector with the receptacle.
When the connector and receptacle are not properly engaged due to the failure of alignment, the possibility of seal failure is increased. Failure of the seal may not only lead to failure of the application but more serious consequences. For example, in the situation described, chemicals used for cleanout of a manifold may be spilled into seawater resulting in environmental hazards. Once more, failure of the seal may also result in damage to the equipment being serviced. That is, the lack of a seal not only means that the fluid from the line does not end up exclusively where intended, it also means that seawater may contaminate the equipment as well. Even if contamination of the equipment with an unintended influx of seawater does not ruin the equipment, it is still likely to result in the need for some level of inspection and/or repair. As a result, operations may be shut down until replacement equipment may be acquired and deployed if available. All in all, the cost of such replacement due to delays in operations may be in the millions of dollars, simply due to the failure to properly install a handheld size bore connector at a piece of equipment on the seabed.
Efforts have been undertaken to improve the reliability of such connector equipment mating. However, there remains no effective manner of ensuring proper alignment for sake of engagement and sealing. For example, currently available connectors are generally mated to the receptacle of the equipment through more of a stabbing technique without any advance focus on alignment. Further, even those that do not utilize such a stabbing technique still do not provide any manner of verifying proper alignment in advance of attaining full engagement. Thus, a substantial risk of misalignment and eventual seal failure remains.